Onchocerciasis is one of the major debilitating parasitic diseases of the world and a major cause of blindness in man. There is currently no effective method for controlling this disease and all the infected individual can hope for is some amelioration of his symptoms. The aim of this study is to investigate the pathology of ocular onchocerciasis using the mouse as a model. An inbred mouse model of ocular onchocerciasis would provide a valuable tool for assessing the effects of new and existing chemotherapeutic agents and potential vaccines. Onchocerca cervicalis is a parasite of horses which also produces serious eye disease. Microfilariae (mf) of O. cervicalis obtained from the skins of infected horses at abbatoirs will be injected into mice to investigate the extent of the anterior and posterior segment pathology which develops. Different inbred strains of mice will be used and mf injected intracorneally or intravitreally. The route(s) by which mf invade ocular tissue and the pathology resulting from intraocular mf injection of naive mice and mice pre-sensitized to living or dead mf will be studied also.